1. Technical Field
This invention generally relates to sealing apparatus for motor vehicle fuel tanks and, more particularly, to a fuel tank filler pipe check valve for preventing unwanted discharge of liquid fuel and fuel vapor into the atmosphere when the fuel cap is removed.
2. Discussion
Automotive fuel tanks are refuelled by means of a filler pipe that carries a detachable cap at its open end. This detachable cap is customarily designed to seal the open end of the filler pipe when it is installed. However, there are instances when the gas cap is not properly installed after refuelling or forgotten altogether.
If the cap is damaged, loose, or not installed, the fill pipe is essentially open. This is an undesirable situation for many reasons particularly since it can effect the unwanted discharge of liquid fuel and fuel vapors into the atmosphere. Without some sort of device, such as, for example, a warning light on the dashboard of the vehicle, the operator would not be aware that the cap is not in place. Therefore, the unwanted discharge will continue unabated until discovered by the vehicle operator.
Most present day passenger vehicles have fuel tanks with filler pipes that are used in conjunction with a fuel dispenser nozzle inserted therein to introduce fuel into the fuel tank. When the tank has been completely filled with fuel, a pressure remains in the tank which forces excess fuel up the filler pipe to the nozzle. This is undesirable since fuel remains in the filler pipe under pressure after refueling.
Therefore, it would be desirable to provide a check valve disposed at a lower end or midstream of a filler pipe which yields under the pressure of inflowing fuel to an open position but seals against fuel and vapor back-flow. In this way, fuel and vapor are prevented from progressing into the filler pipe after the fuel tank has been filled to maximum capacity.